This application is a 371 of PCT/JP98/01010 filed of Mar. 11, 1998.
The present invention relates to a test device for analysis of components contained in liquid samples, particularly aqueous solutions such as blood and urine.
A simple test device for analysis of a liquid sample by reaction with a reagent generally utilizes capillary action for introduction or transfer of a sample to a site for reaction with the reagent in the test device. As this test device, there are the type of device where a reagent applied onto a capillary tube comes to be dissolved in a sample and the type of device where a sample penetrates into a reagent layer provided on a capillary tube.
As an example of the former, JP-A63-274839 describes a test device comprising a lower stretching member also serving as a shaft and an upper member containing a reagent while forming a capillary tube via a spacer with said lower member. As an example of the latter, JP-A 4-188065 describes an analytical device comprising a carrier, a reagent layer sealed to the carrier, and a cover which while covering the reagent layer, is fixed so as to form a capillary chamber with the carrier, said cover having a sample feed opening and an air outlet.
However, in the type of device where a reagent comes to be dissolved in a sample, such as in the test device described in JP-A 63-274839, the concentration of a reaction solution should be accurately defined, so a sample to be fed should previously be introduced into a vessel with a known volume such as pipette. Further, in the type of device where a sample penetrates into a reagent layer, such as in the test device described in JP-A 4-188065, the reagent should be contained in a paper or a film separate from a capillary tube and then fixed to the capillary tube in order to maintain the volume of the reagent layer.
Accordingly, the object of the present invention is to provide a test device which can easily measure a predetermined amount of a sample and simultaneously analyze the sample without pipetting the sample into another vessel or separately preparing a reagent layer for fixing the sample.
To achieve the object, the test device of the present invention is a test device for analyzing a specific component in a test solution with a reagent by allowing the test solution introduced via a test solution feed opening to react with the reagent maintained in a predetermined position in a capillary tube having the feed opening and an air outlet, said capillary tube comprising:
a first hydrophilic region for transferring the test solution from the test solution feed opening to the reagent,
a second hydrophilic region having a predetermined area maintaining the reagent, and
a hydrophobic region which separates the first hydrophilic region from the second hydrophilic region and communicates with the air outlet without passing through the first and second hydrophilic regions.
According to this test device, a test solution introduced via the test solution feed opening advances by capillary action through the first hydrophilic region to the reagent. Simultaneously, the air in the capillary tube is pushed out and discharged from the air outlet. Once the test solution reaches the hydrophobic region, its transfer is prevented transiently by the hydrophobic region. Then, when external force is applied to the test device, the test solution pass through the hydrophobic region to transfer to the second hydrophilic region.
Because the area of the second hydrophilic region is constant, the amount of the test solution maintained therein is determined by its area and the internal diameter of the capillary tube. When the test solution passes the hydrophobic region to transfer to the second hydrophilic region, the test solution remaining on the hydrophobic region or the solution which cannot be maintained on the second hydrophilic region is removed by repulsion by the hydrophobic region. Accordingly, it is not necessary to pipette the test solution previously into a vessel having a known volume or to maintain the reagent in a layered predetermined area. Further, because the region maintaining the reagent is hydrophilic, the reagent can be fixed to the second hydrophilic region by merely applying it. By reaction between a predetermined amount of the maintained test solution and the reagent, a specific component in the test solution can be analyzed highly accurately.
External force applied to permit the test solution to pass through the hydrophobic region includes e.g. instantaneous vibration or centrifugal force by shaking the test device by the hand of an operator, suction force by suction through the air outlet, and pressurization through the feed opening.
The air outlet is preferably a penetration hole formed in such a direction that it intersects the capillary tube. By forming the penetration hole in this way, the capillary tube can be formed into a tube where excluding the penetration hole, the test solution feed opening only is open, and the overflow of the test solution maintained in the second hydrophilic region can be prevented. The angle at which the penetration hole intersects the capillary tube at the side of the first hydrophilic region is preferably an acute angle. By this constitution, when the test solution is transferred by external force to the second hydrophilic region, it can stop flowing from the penetration hole, thus preventing biohazard.